Route reliability record
SEA→AUS
Seattle to Austin
- Flights
- 2,059
- Period
- July 2025 to June 2026
- Distance
- 1,770 mi
- Carriers
- 3
This route lands a B+, 2 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 2,059 SEA to AUS flights, of which Delta Air Lines flew 936 at 81.0% on time.
Best time to fly SEA to AUS: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 89.1% of the time and Tuesday flights 87.6%, against 79.1% for the route overall.
The US average over the same twelve months is 77.6%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.1%
Arrivals under 15 minutes late, of 2,036 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.97%
National rate is 1.81%
Best carrier
Delta
81.0% on time across 936 flights
These figures cover 2,059 flights between July 2025 and June 2026. The median arrival is 4 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
Carrier by carrier
Which airline is most reliable on SEA to AUS
The two carriers here are closely matched: 3 points separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 936 | 81.0% | 72 min | 1.28% | B |
| Alaska Airlines | 1,096 | 78.4% | 48 min | 0.73% | B+ |
| Southwest Airlinesthin sample | 27 | 40.7% | 42 min | 0.00% | F+ |
No carrier stands out. Delta tops the table at 81.0%, 3 points clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on SEA to AUS
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
Best ways to make this trip
The most reliable ways to fly Seattle to Austin
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SEA → AUSSeattle to Austin | Delta Air Lines | 80.0% | 81.0% | 1.28% | 5am–8am, Tue | DL 739 07:20 |
| 2. SEA → AUSSeattle to Austin | Alaska Airlines | 77.8% | 78.4% | 0.73% | 8am–11am, Tue | AS 502 09:03 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 17 points, against 3 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am278 flights89.1%
- 8am–11am482 flights83.7%
- 11am–2pm612 flights78.2%
- 2pm–5pm12 flights—
- 5pm–8pm595 flights73.8%
- 8pm–5am80 flights72.5%
Scale runs 65% to 95%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 89.1% of the time, against 72.5% for the overnight window. That is 17 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 612 flights scheduled in it.
Across the year
When delays peak on this route
This route's year swings by 28 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 60.2% on time, 28 points below April, the best at 88.2%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 208 flights.
Across the week, Tuesday is the strongest day at 87.6% on time and Friday the weakest at 73.4%. 14 points is a smaller lever than departure hour, but it is free.
Delay causes
Why this route gets delayed
One category carries most of the weight here. Carrier accounts for 44% of the 24,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 44%Carrier
- 29%Late-arriving aircraft
- 24%National Airspace System
- 2%Extreme weather
- 0%Security
The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 11,000 of the 24,000 delay minutes reported here. The split is drawn from 24,364 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 89.1% on time here.
Cancellations sit at 0.97% against a national 1.81%, which is ordinary. Diversions add another 0.15%.
Connections and stage length
What a delay here actually costs
5.5% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
At 1,770 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 82.8% on time across 2,058 flights, 4 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 4 points of difference.
The sample behind these figures is 2,059 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in AUS after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 88.2% on time and July 60.2%, a swing of 28 points. If the dates move at all, move them out of July before you think about anything else. 2,036 completed flights over 12 months sit behind that.
Common questions
SEA to AUS questions
How often is SEA to AUS delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 20.9% of the 2,059 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on SEA to AUS?
Delta Air Lines leads at 81.0% on time across 936 flights. Alaska Airlines is at the other end on 78.4%, a gap of 3 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on SEA to AUS?
The 5am–8am departure window is the strongest at 89.1% on time. The 8pm–5am window is the weakest at 72.5%, 17 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on SEA to AUS?
July is the weakest month at 60.2% on time, compared with 88.2% in April. Across the year that is 28 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- AUS to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Austin-Bergstrom International (AUS) delay statistics
- Delta Air Lines on SEA to AUS81.0%
- Alaska Airlines on SEA to AUS78.4%
- SEA to LAX, a related route83.4%
- DEN to AUS, a related route76.1%
- SEA to PHX, a related route79.2%
- Delta Air Lines on-time record81.0%
- Alaska Airlines on-time record78.4%
- Southwest Airlines on-time record40.7%
- The best time of day to fly, according to 7.04 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. SEA to AUS and AUS to SEA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.